Heat exchange unit



' March 23, 1944; Q R, KgEp HEAT EXCHANGE UNIT Original Filed May 16,1942' fewer 222 Cimwea Elifeep,

Patented Mar. 28,

nmr nxcmmon um'r Charles B. Keep, Nor-wood, Mass assignor to B. F.Sturtevant Company, Boston, Mass.

original application May 16, 1942, serial No. 443,203. Divided and thisapplication January 1, 1943, Serial No. 471.048

3 Claims. '(CL 257-137) This invention relates to heat exchange units ofthe type which contain air ejector nozzles through which primary airfrom a central source is supplied for inducing the flow into the units.of recirculated air.

This application is a division or my oopending application, Serial No,443,203, filed May 16.

The Palmer Patent No. 2,287,267 discloses such a unit in which theexternal surfaces of the heat exchange tubes are shaped and arrangedtoform the ejectors for inducing the flow of recirculated air. Thepresent invention provides improvements over the features disclosed insaid patent and which modify same for overcoming difllculties ofcommercial operation.

A feature of this invention resides in providing for varying theinduction effect of ejectdr nozzles utilizing surfaces of heat exchangetubes.

In one embodiment of the invention, the opposite walls of the ejectornozzle are formed by elongated heat exchange tubes, one or both of thetubes-having extensions at the tips thereof and one of the extensionsbeing pivoted for varying the spacing between the nozzle tips and thusvarying the ejector effect. 7

Another feature of the invention resides in providing an air by-passaround an ejector nozzle which includes one or more heat exchange tubesas an element or elements thereof. In the embodiment' of the inventionutilizing heat exchange tubes as opposite walls of an ejector nozzle, anair by-pass is provided by utilizing two recirculated air inlets, onebelow and the other above the ejector.

Objects oi the invention are to improve the efiiciency of and to reducethe cost of, heat ex-' change units of the typ which include ejectornozzles for inducing the flow of recirculated air.

The invention will now be describedWith reference to the drawing, ofwhich:

Fig. 1 is a cross sectional view through one embodiment of a heatexchange unit incorporating features of this invention, and

Fig. 2' is a side elevation of the unit of Fig. 2.

Two heat exchange tubes l0 provide the opposite converging walls of anejector nozzle as disclosed in said patent. The tubes are provided withthe fins 15 which extend from the outer surfaces of the tubes to thewalls 6. All of the recirculated air from the inlet 8 passes in contactwith the fins IS.

A bypass around the heat exchange surfaces for recirculated air isprovided by another recirculated air inlet 22 placed between the tubesi8 and the air outlet 9. The inlet 8 contains the shutter type dampers23 and the inlet 22 contains the similar dampers 24. The dampers 23 and24 are interconnected by the rod 25 and "are simultaneously adjusted bythe knob 26. The

dampers 23 are opened when the dampers 24 are closed and vice versa sothat as the volume of bypass air through the inlet 22 is increased, thevolume of recirculated air trhough the inlet 23 is decreased. Thedeflector 32 prevents the outward flow of air through the inlet 22.

The ejector nozzle adjustment is taken care of by attaching thestationary plate extension 27 to the upper end of one of the tubes itand by pivoting the plate extension 28 to the upper end of the other ofthe tubes. The rod 29 is attached to the plate 28 and is moved by theknob 30 for varying the space between the plates 27 and 28 andaccordingly the airinducing effect of the nozzle.

The pipe-3i illustrated by Fig. 2 may be one of two pipes for conveyingheat exchange fluid to the tubes iii. The tubes have internal openingsIs for the passage of a heat exchange fluid therethrough for temperingthe primary and recirculated air. In hot weather, a chilled brine orother suitable fluid may be used. In cold weather steam or hot water maybe used.

The duct I4 is adapted to be connected to a central source of primary,conditioned air under sumcient pressure for the ejector nozzle to inducethe desired volumes of recirculated air and for the mixed primary andrecirculated air to be discharged at sufllcient velocity and undersufficient pressure to convey the discharged air to remote points in thespace served.

Advantages of utilizing the surface of an elongated tube ill as anejector wall are that saving in materialresults; that improved heattransfer is obtained due to the absence of the turbulence and the shadoweffect of round tubes; the operation is quieter, the efliciency isgreater and the elongated tubes and their fins may be cast iron, amaterial more easy to obtain than copper under emergency conditions.

While an embodiment of the invention has been described for the purposeof illustration, it should be understood that the invention is notlimited to the exact apparatus and arrangements of apparatusillustrated, as modifications therefrom may be suggested by thoseskilled in the art without departure from the essence of the invention.

What is claimed is:

1. A substantially rectangular heat exchange unit having substantiallyvertically extending walls, a discharge outlet in its upper wall, arecirculated air inlet in the lower portion of one of said verticallyextending walls, and a primary air inlet, comprising a pair of elongatedheat exchange tubes arranged to form between adjacent external surfaces,an upwardly extending elector nozzle, said tubes having internalopenings for the passage of a heat exchange fluid and having extendedsurface fins extending from one tube to said one of said wallsandextending from the other tube to the wall of said unit opposite saidwall, means forming a passage conducting air from said primary air inletinto said nozzle and forming walls isolating the air from said primaryinlet from the air from said recirculated air inlet, means forminganother recirculated air inlet in said one wall between said nozzle andsaid outlet, dampers in said recirculated air inlets, and means at theupper ends ofsaid tubes for "varying the induction efiect of said nozzlefor varying the volume of air drawn in through said recirculated airinlets. v

2. A substantially rectangular heat exchange unit having substantiallyvertically extendin'g walls, a discharge outlet in its upper-wall, arecirculated air inlet in the lower portion of one of said verticallyextending walls, and a primary air inlet, comprising a pair of elongatedheat exchange tubes arranged to form between adjacent external surfaces,an upwardly extending ejector nozzle, said tubes having internalopenings for the passage of a heat exchange fluid and having extendedsurface fins extending from one tube to said one of said walls andextending from the other tube to the wall of said unit 0pposite saidwall, means forming a passage conducting air from said primary air inletinto said nozzle and forming walls isolating the air from said primaryinlet from the air from said recirculated air inlet, and means at theupper ends of said tubes for varying the induction effect of said nozzlefor varying the volume of air drawn in through said recirculated airinlet.

3. A substantially rectangular heat exchange unit having substantiallyvertically extending walls, a discharge outlet in its upper wall, arecirculated air inlet in the lower portion of one of said verticallyextending walls, and a primary air inlet, comprising a pair of'elongatedheat exchange tubes arranged to form between adjacent external surfaces,an upwardly extending ejector nozzle, said tubes having internalopenings for the passage of a heat exchange fluid and having extendedsurface fins extending from one tube to said one of said walls andextending from the other tube to the wall of said unit opposite saidwall, means forming a passage conducting air from said primary air inletinto said nozzle and forming walls isolating the air from said primaryinlet from the air from said recirculated air inlet, and means includinga pivoted extension of one of said tubes at the upper ends of said tubesfor varying the induction effect of said nozzle for varying the volumeof air drawn in through said recirculated air inlet.

CHARLES R. KEEP.

